Apparatus for automatic operation of a choke valve in a carburetor

ABSTRACT

A choke valve in a carburetor is controlled by a temperature sensitive element which is directly coupled with a cam in turn coupled to the choke valve so that the valve will be moved in opposite directions in accordance with temperature variation of the engine irrespective of the contact of an operating member of a throttle valve with the cam.

UnitedStates Patent lsamu Goto Tokorozawa-shi;

Minoru Inada, Kitaadachi-gun; Minoru Atsumi; Toyoshige Miyazaki, Tokyo;Mitsuaki Ninomiya, Yokohama-shi, Japan lnventors APPARATUS FOR AUTOMATICOPERATION OF A CHOKE VALVE IN A CARBURETOR [56] References Cited UNITEDSTATES PATENTS 1,921,736 8/1933 Erade 26l/52X 2,400,035 5/1946 Weber...261/39(.l)X 2,478,613 8/1949 Weber 26l/52X 2,681,213 6/1954 Gordon261/52X 2,774,343 12/1956 Schaffer et a1. 261/39(.1)X 2,815,942 12/1957Olson 261/52 2,868,522 1/1959 ONeil 261/39(.1)X 2,998,233 8/1961 Marsee261/39(.3) 3,151,189 9/1964 McSeveny 261/39(.1) 3,291,462 12/ l 966Mennesson.... 26l/39(.1)

Primary Examiner-Tim R. Miles At!orneyWaters, Roditi, Schwartz and Nissen ABSTRACT: A choke valve in a carburetor is controlled by atemperature sensitive element which is directly coupled with a cam inturn coupled to the choke valve so that the valve will be moved inopposite directions in accordance with temperature variation of theengine irrespective of the contact of an operating member of a throttlevalve with the cam.

11 Claims, 2 Drawing Figs.

US. Cl 261/39, 261/52 Int. Cl F02m 3/06 Field of Search 39.2,52

i rm i I I U IT 84 29 8 1 a X? Ti 7 I2 I \AL FL G h ,2 I/ Q A}- 3 25 w 9A? Z5 7 2 e o Patented M 20, 1911 3,575,389

' 2 sheets-Suki 1.

Y mvzm'gn I MAM Patented April 20, 1971 2 Sheets-Sheet 2 APPARATUS IFORAUTOMATIC OPERATION OF A CIIIOIIE VALVE IN A CARBURETOR BRIEF SUMMARY OFTHE INVENTION This invention relates to the operation of choke valves incarburetors.

It has been known hitherto that a choke valve in an internal combustionengine for a motorcar, or the like, is provided with a bimetallicelement responsive to engine temperature so that the choke valve may beopened automatically as the engine temperature rises. It has also beenknown hitherto that such choke valve may be provided with a cam foradjusting the degree of opening of a throttle valve so that it increasesas the degree of opening of the choke valve is decreased, whereby theengine may properly idle even when cold, In the conventional apparatusas known, however, if the cam connected to the choke valve has beenengaged with the throttle valve and thereby the degree of opening of thethrottle valve is adjusted by the cam, and moreover since the engagingforce between the two is stronger than the operation force of thebimetallic element (the throttle valve is provided with a valve closingspring of strong force for being brought into engagement with the cam),if the engine temperature is subsequently changed, the cam, the chokevalve and the throttle valve are immovably retained in that conditionand there cannot be effected automatic adjustment of these valves.Accordingly, an unavoidable inconvenience is produced in order to obtaina complete adjustment, namely while the engine is cold, the throttlevalve must be manually opened to release the engagement between the camand the throttle valve so as to free the cam.

An object of this invention is to provide a simple and effectiveapparatus which overcomes the above inconvenience and in which thedegree of opening of the choke valve can always be adjustedautomatically according to the engine temperature regardless of whetherthe cam connected to the choke valve is in engagement with the throttlevalve or not.

In accordance with the invention, there is provided apparatus for theautomatic operation of a choke valve which comprises a throttle valve, arotatable cam having a smooth, continuous cam surface for adjusting thedegree of opening of the throttle valve, a choke valve coupled to saidcam for rotation therewith, a member coupled to said throttle valve formovement therewith to contact said cam surface so that the degree ofopening of the throttle valve at idle may be increased as the degree ofopening of the choke valve is decreased, strong valve closing springmeans for closing the choke valve and a temperature sensing device ofstrong expansion force coupled to said choke valve and includingtemperature expansion means for expanding upon receiving heat from aninternal combustion engine to cause the degree of opening of the chokevalve to be automatically adjusted according to the engine temperatureregardless of whether the cam surface and said member are in contact onewith another.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a side view, partly insection, of the apparatus of this invention, and

FIG. 2 is a sectional view taken along line lI-ll in FIG. 1.

DETAILED DESCRIPTION Referring to FIG. 1, numeral I denotes acarburetor, numeral 2 denotes a suction air passage thereof, numeral 3denotes a choke valve and numeral 4 denotes a rotatable shaft of thechoke valve attached at a position displaced upwards from the center ofthe suction air passage 2. Numeral 5 denotes a cam rotatably mounted ona shaft portion 1A (FIG. 2) projecting from the carburetor I andconnected to the choke valve shaft 4 as will be explained hereinafter.Numeral 5A denotes a cam surface of cam 5. Numeral 6' denotes a throttlevalve mounted on a rotatable shaft 7, and numeral8 denotes a throttlevalve lever rigidly connected to the shaft 7 and having at its top end acontact number 8A adapted for contacting the cam surface 5A. Numeral 9denotes a return spring attached to the throttle valve lever 8 forurging the throttle valve 6 in its closing direction, numeral 10 denotesan adjustable stop member for establishing the closing limit of thethrottle valve 6, and numeral II denotes an operation cable for manuallyopening the throttle valve 6 through the throttle valve lever 8. Asclearly shown in FIG. 2, a supporting plate 12 having an engagingportion 12A is fixed to the choke valve shaft 4 and a weak spring I4 isinterposed between engaging portion 12A and a stopper l3 projecting fromthe cam 5 to urge portion 12A toward stopper 13. Accordingly, if theamount of suction air is increased when the choke valve 3 closes thesuction air passage 2, the choke valve 3 is opened against the action ofthe spring 14 by the suction air pressure and thereby the suction airamount is increased. The above is a conventional construction.

The carburetor l is provided with a supporting housing 15 fixed thereto,and there is fixedly provided below the housing a temperature sensingdevice 16 adapted to produce a strong thermal expansion force. Thistemperature sensing device 16 comprises, for example, a tightly closedouter tube 17, a supporting pipe 18, which is fixed in the interiorthereof and is opened at its lower end, and a thermal expansion materialsuch as ether enclosed between the two. A movable rod 20 is inserted inthe supporting pipe 18 and a slidable sealing member 21 is tightlymounted in the supporting pipe 18 below the lower end of the movable rod20. Numeral 22 denotes a tubular housing member for the temperaturesensing device 16 and member 22 has an inlet 23 and an outlet 24 for afluid so that the temperature sensing device 16 may be kept nearly equalto the engine temperature by the engine exhaust gases or the lubricationoil, or the like, flowing therein through the inlet 23. The carburetor Iis provided with a multiplication lever'26 pivoted at 25, and a pin 28provided at the top end of the movable rod 20 is loosely mounted in aslot 27 formed in one end of the lever 26 the other end of which isconnected to the cam 5 through a connecting rod 29'. Numeral 30 denotesa spring receiving-plate fixed to the'middle of the movable rod 20 andnumeral 31 denotes a strong valve closing spring urging the movable rod20 toward the temperature sensing device I6. Accordingly, if thetemperature of the engine increases, as measured by the temperaturesensing device 16, the thermal expansion material 19 is expanded todisplace the movable rod 20 from the temperature sensing device 16against the action of the valve closing spring 31- and the movement ofrod 20 is multiplied by the lever 26 for opening the choke valve 3. Ifthe temperature of the temperature sensing device 16, that is, theengine is lowered, the thermal expansion material 19 is contracted sothat in' accordance therewith the movable rod 20 is displaced into thetemperature sensing device 16 by the valve closing spring 31 for closingthe choke valve 3. In the case when the engine temperature is lower thanthe ordinary operation temperature thereof, the contact member 8A of thethrottle valve lever 8 is pressed strongly against the cam surface 5A ofthe cam 5 by the return spring 9 and there is caused a large frictionforce between thecam surface and the contact member. However, inaccordance with this invention, his so arranged that the choke valve 3is operated by the temperature sensing device of strong expansion forceand the strong valve closing spring 31 and, additionally, the camsurface 5A is formed as a smooth continuous curved surface, so that theexpansion force of the temperature sensing device 16 and the resilientforce of the valve closing spring 31 can overcome the friction forcementioned'above, whereby the choke valve 5 may be always rotatedautomatically in accordance with the change of the, engine temperatureand, at the same time, the degree of opening of the throttle valve isautomatically adjusted in accordance therewith.

Thus, according to this invention, it is possible that the choke valveand the throttle valve are always automatically adjusted positively inaccordance with the variation of engine temperature so that it is notrequired that the throttle valve operating cable ll be manually operatedas in conventional arrangements.

We claim:

1. Apparatus for the automatic operation of a rotatable choke valve in acarburetor, said apparatus comprising a throttle valve, a rotatable camhaving a smooth. continuous cam surface for adjusting the degree ofopening of the throttle valve, a choke valve coupled to said cam forrotation therewith about a common axis, a member coupled to saidthrottle valve for movement therewith about a common axis, said memberresting in peripheral contact with said cam surface to follow rotationof said choke valve and cause the degree of opening of the throttlevalve at idle to increase as the degree of opening of the choke valve isdecreased, strong valve closing spring means for closing the choke valveand a temperature sensing device of strong expansion force coupled tosaid choke valve and including temperature expansion means for expandingupon receiving heat from an internal combustion engine to cause thedegree of opening of the choke valve to the automatically adjustedaccording to the engine temperature regardless of whether the camsurface and said member are in contact one with another.

2. Apparatus as claimed in claim 1 wherein said member is in frictionalcontact with said cam surface when the engine temperature is below apredetermined operating temperature, said temperature expansion meansapplying a force to said cam to turn the same against the frictionalforce of the contact of the cam with said member to open the choke valveas the engine temperature increases.

3. Apparatus as claimed in claim 2 wherein said temperature expansionmeans acts in opposition to said spring means.

4. Apparatus as claimed in claim 2 wherein said temperature expansionmeans comprises a temperature sensitive element and a displaceable rodcoupled to said LII element and said cam for rotating the latter as theelement senses increased temperature.

5. Apparatus as claimed in claim 4 wherein said temperature sensitiveelement comprises an enclosed chamber containing a substance whichexpands with increasing temperature, and means for passing a substancewhose temperature is a measure of engine temperature into contact withsaid enclosure, said rod extending into said enclosure and beingdisplaced by expansion of the substance therein.

6. Apparatus as claimed in claim 5 wherein said strong valve closingmeans acts on said rod to urge the same into the enclosed chamber, saidvalve closing means having a sufficient strength to displace the rodagainst the frictional force of contact of said member with the camsurface.

7. Apparatus as claimed in claim 6 comprising a lever between said rodand cam for multiplying the effect on said cam of the displacement ofsaid rod.

8. Apparatus as claimed in claim 6 wherein said means for passing thesubstance whose temperature is a measure of the engine temperature intocontact with the enclosure comprises a housing surrounding saidenclosure and an inlet and an outlet in said housing for said substance.

9. Apparatus as claimed in claim 8 wherein said enclosure ishermetically sealed and said substance in the enclosure is a fluid.

10. Apparatus as claimed in claim 9 wherein said rod is vertical andmoves upward during expansion of the fluid substance and downwards underthe action of the spring means.

ll. Apparatus as claimed in claim 2 wherein said strong valve closingmeans comprises a spring having a strength to close the choke valveagainst the opposition ol the friction force of contact of the cam withsaid member.

1. Apparatus for the automatic operation of a rotatable choke valve in acarburetor, said apparatus comprising a throttle valve, a rotatable camhaving a smooth, continuous cam surface for adjusting the degree ofopening of the throttle valve, a choke valve coupled to said cam forrotation therewith about a common axis, a member coupled to saidthrottle valve for movement therewith about a common axis, said memberresting in peripheral contact with said cam surface to follow rotationof said choke valve and cause the degree of opening of the throttlevalve at idle to increase as the degree of opening of the choke valve isdecreased, strong valve closing spring means for closing the choke valveand a temperature sensing device of strong expansion force coupled tosaid choke valve and including temperature expansion means for expandingupon receiving heat from an internal combustion engine to cause thedegree of opening of the choke valve to the automatically adjustedaccording to the engine temperature regardless of whether the camsurface and said member are in contact one with another.
 2. Apparatus asclaimed in claim 1 wherein said member is in frictional contact withsaid cam surface when the engine temperature is below a predeterminedoperating temperature, said temperature expansion means applying a forceto said cam to turn the same against the frictional force of the contactof the cam with said member to open the choke valve as the enginetemperature increases.
 3. Apparatus as claimed in claim 2 wherein saidtemperature expansion means acts in opposition to said spring means. 4.Apparatus as claimed in claim 2 wherein said temperature expansion meanscomprises a temperature sensitive element and a displaceable rod coupledto said element and said cam for rotating the latter as the elementsenses increased temperature.
 5. Apparatus as claimed in claim 4 whereinsaid temperature sensitive element comprises an enclosed chambercontaining a substance which expands with increasing temperature, andmeans for passing a substance whose temperature is a measure of enginetemperature into contact with said enclosure, said rod extending intosaid enclosure and being displaced by expansion of the substancetherein.
 6. Apparatus as claimed in claim 5 wherein said strong valveclosing means acts on said rod to urge the same into the enclOsedchamber, said valve closing means having a sufficient strength todisplace the rod against the frictional force of contact of said memberwith the cam surface.
 7. Apparatus as claimed in claim 6 comprising alever between said rod and cam for multiplying the effect on said cam ofthe displacement of said rod.
 8. Apparatus as claimed in claim 6 whereinsaid means for passing the substance whose temperature is a measure ofthe engine temperature into contact with the enclosure comprises ahousing surrounding said enclosure and an inlet and an outlet in saidhousing for said substance.
 9. Apparatus as claimed in claim 8 whereinsaid enclosure is hermetically sealed and said substance in theenclosure is a fluid.
 10. Apparatus as claimed in claim 9 wherein saidrod is vertical and moves upward during expansion of the fluid substanceand downwards under the action of the spring means.
 11. Apparatus asclaimed in claim 2 wherein said strong valve closing means comprises aspring having a strength to close the choke valve against the oppositionof the friction force of contact of the cam with said member.